Dynamic fin comprising coupled fin sections

ABSTRACT

A dynamic or aerodynamic fin comprising at least two parallel arranged fin sections. At least one fin section comprises a rotational axis for installing the fin section by a rotation shaft. An end stop is provided for stopping the rotational movement of the fin section to define an extreme position. In the extreme position the fin sections provide a substantially cambered shape to the fin. The dynamic fin is improved in that it comprises a pair of coupling elements. A first fin section is coupled to a second adjacent fin section by a pair of a first and second coupling elements. The first coupling element is complementary to the second coupling element. The first coupling element is part of, preferably integral, with the first fin section and the second coupling element is part of, preferably integral, with the second fin section.

BACKGROUND OF THE INVENTION

The present invention relates to a dynamic fin which comprises at leasttwo parallel arranged fin sections. An orthogonal coordinate systemincluding a first, second and third axis can be defined, wherein the finsections extend in a direction of the first axis. Generally, this firstdirection is also regarded as the longitudinal direction. At least onefin section comprises a rotational axis for installing the fin sectionby a rotation shaft in for example a mounting box. The rotational axisextends in the direction of the fin section and enables a rotationalmovement of the fin section. An end stop is provided for stopping therotational movement of the fin section to define an extreme position. Inthe extreme position the fin sections provide a substantially camberedshape to the fin. This cambered shape improves the hydro- or aerodynamicproperties of the fin. In the other extreme position the fin may foam amirrored cambered shape in comparison with the cambered shape in thefirst extreme position.

Such a dynamic, in particular dynamic fin is known from the Americanpatent U.S. Pat. No. 5,181,678. In FIG. 14 of this American patent, afin is shown, which is build from multiple rigid fin sections. The finsections are joined together by means of hinges. Two adjacent finsections are provided with holes which form a first part of the hinge.The holes of two adjacent fin sections can be aligned, were after anadditional pen can be mounted to complete the hinge.

Such a pin-hole hinge construction between adjacent fin sections bringssome problems. A first problem relates to the manufacturing of the finsections. To manufacture the fin section, some extra machiningoperations like milling and drilling are necessary to manufacture theholes in the fin sections. Especially, in an embodiment of the dynamicfin for a surfboard, wherein the pin-hole hinge has to be very small, itmay be a major problem to manufacture the hinge because of a limitedavailable space for machining tools to access the fin. Generally, thefin sections are made from a basic shape which is manufactured bymachining of a prefab plate material, like epoxy plate which may bereinforced by glass fibres e.g. G10 or moulding of a laminated prepregmaterial, like epoxy including glass-fibres or carbon-fibres orinjection moulding of a polymer material.

Further operations are necessary, to provide the fin with the pin-holehinge construction. The construction of the pin-hole is rather detailedwhich complicates the manufacturing and the assembling of thecomponents. Those further operations increase production efforts andcosts.

Another problem of the known hinge-construction is that it issusceptible for contamination. An environment with dirt, sand or saltmay cause a failure of the pin-hole hinge construction.

It is an object of the present invention to overcome at least partiallyone or more of the above-mentioned drawbacks and/or to provide a useablealternative. In particular, the invention aims to provide a dynamic finwhich is more simple to manufacture and/or to assemble and thus morecost effective and more durable.

This objective is achieved by a dynamic fin as defined in claim 1.

A dynamic fin according to the invention comprises at least two parallelarranged fin sections. An orthogonal coordinate system including afirst, second and third axis can be defined, wherein the fin sectionsextend in a direction of the first axis. Generally, this first directionis also regarded as the longitudinal direction, wherein the fin sectionsextend away from a base which may define a base plane including thesecond and third axis. The base plane may be flat. The third axis isgenerally regarded as an outward direction which extends away from thesubstantially smooth and flat outer surfaces of the fin. At least onefin section comprises a rotational axis for installing the fin sectionby a rotation shaft to for example a mounting box. The rotational axisextends in the direction of the fin section and enables a rotationalmovement of the fin section. An end stop is provided for stopping therotational movement of the fin section to define an extreme position. Inthe extreme position the fin sections provide a substantially camberedshape to the fin. This cambered shape improves the hydro- or aerodynamicproperties of the fin.

The dynamic fin according to the invention is improved in that itcomprises a pair of coupling elements. According to the invention afirst fin section is coupled to a second adjacent fin section by a pairof a first and second coupling element. The first coupling element iscomplementary to the second coupling element. The coupling elementsprovide a coupling of adjacent fin sections in a direction of the thirdaxis. The third direction is a direction outwards the outer surface offin. Herewith, the second adjacent fin section will follow a rotationalmovement of the first fin section in the third direction around thefirst axis. The relative rotational movement of the fin sections makesthe fin dynamic. If the first fin section rotates clockwise, the secondcoupled fin section will rotate counter-clockwise.

The first coupling element is part of, preferably integral, with thefirst fin section and the second coupling element is part of, preferablyintegral, with the second fin section. Preferably, the coupling elementsare made of the same material as the fin sections. Herewith,advantageously, the coupling elements may be integrally manufactured tothe fin sections, by for example moulding or machining. The insight thatonly a coupling in the direction of the third axis, which is generallythe transversal direction, between two adjacent fin sections isnecessary, instead of a hinge with a pin and a hole gives the advantagethat the dynamic fin may be manufactured by just a few operations. Nocomplex shapes, like slotted holes with accurate tolerances need to bemade. No extra components like pins are needed to assemble the dynamicfin. The complete dynamic fin may be easier to assemble as a result ofthe more simple connection between the fin sections.

A further advantage is that instead of a permanent hinge construction,the coupling may be released manually. This may be advantageous forexample for cleaning the fin. It may even be possible to release thecoupling without a hand tool. Especially in a rough environment withmud, sand and salt this may be advantageous. The fin according to theinvention may be easy disassembled to clean the fin sections. Cleaningthe fin sections may improve the lifetime of the fin. Preferably, thecoupling elements are rigid which allows well-defined extreme positionsand may reduce a risk of damages.

In an embodiment of the dynamic fin according to the invention, the finsections are rotatable from one extreme position to another extremeposition under a substantially constant resistance. No springs orelastic materials are provided which would substantially increase theresistance from a nominal position to an extreme position. Thesubstantially constant resistance may increase the effectiveness of thedynamic fin. This substantially constant resistance allows the finsections to change quickly from one camber into another. The finsections may get already into one of the extreme positions, while thedynamic forces on the fin are still relative small. The degree ofrotation of the fin sections may be independent of the amount of thehydro- or aerodynamic force on the fin. Herewith, the fin provides asubstantially increase of effectiveness, which may be already availableat a low speed.

In a particular embodiment of the dynamic fin according to theinvention, the first coupling element is formed by a groove whichextends in the first direction, which is generally the longitudinaldirection, along an edge of the first fin section. Preferably, thegroove extends over substantially the whole length over the first finsection. An adjacent fin section having a complementary coupling elementmay be coupled to the first fin section by inserting the second couplingelement into the groove. It may be advantageous when the couplingelements extend over substantially the whole length of the fin sections,because this may improve an alignment of the fin sections and mayprovide a strong coupling which may withstand a bigger hydro- oraerodynamic load.

The groove of the first coupling element defines a receiving openinginto which the complementary coupling element of the second fin sectioncan be inserted, e.g. by sliding of the fin sections in the longitudinaldirection. Preferably, the second coupling element may be formed by anouter tongue which is complementary shaped with respect to the groove ofthe first coupling element. The tongue may extend in a longitudinaldirection along an edge of the fin section. The complementary groove andtongue may be positioned onto a section surface of the adjacent finsections. The section surfaces may be brought opposite to each other toassemble the tongue into the groove, e.g. by sliding the fin sectionsrelative to each other in the longitudinal direction.

Preferably, the cross section of one or both coupling elements issymmetrical to allow a symmetrical rotational movement of adjacent finsections from a nominal position. The cross section may have an axis ofsymmetry which extends in a direction of the second axis of theorthogonal coordinate system.

In a preferred embodiment of the dynamic fin according to the invention,the first and/or the second coupling element comprise in thelongitudinal direction a constant shape in a cross section, inparticular parallel to a plane in the second and third direction. Thisconstant shape may be advantageous because it may provide an opportunityto manufacture the fin section including the coupling element bymachining or moulding. The constant shape allows a removal of the finsection including the coupling element out of a mould in just onedirection. Advantageously, due to the constant shape, the mould mayremain of a simple design.

In a further preferred embodiment the constant shape becomes smaller indimensions in a direction from a base or foot of the fin to a tip of thefin section. The smaller dimensions to the tip of the fin section mayprovide an improved removal from the mould. Additionally, a furtheradvantage occurs during use of the dynamic fin. The decreasingdimensions of the constant shape of the coupling element provide aunique way to assemble two fin sections. During assembly of the two finsections the corresponding coupling elements may slide along each otherin the longitudinal direction until the coupling elements engage to eachother. Herewith, the dimensions of the shape of the coupling elements inthe longitudinal direction define the positioning of the fin sections.The simple way of sliding the coupling elements along each otherprovides advantageously an easy way to mount or demount the dynamic fin.This may be useful, for example to clean or otherwise service or inspectthe dynamic fin. Herewith, the fin sections may be easily manuallyreleasable without any further tools to remove bolts, pins or the like.The simple and smart releasing of the fin sections may be robust whichmay decrease the risks of damaging the fin during mounting anddemounting.

In a further embodiment of the dynamic fin according to the inventionthe groove of the first coupling element comprises in a cross section,parallel to the plane defined by the second and third axis, an innerrounded, in particular circular part for receiving a second couplingelement which comprises an outer rounded, in particular circular part ina transversal cross section. The circular cross sections define roundedouter surfaces which may improve the rotational movement of the finsections with respect to each other. Advantageously, adjacent finsections may better fit to each other to prevent leakages of fluidthrough the coupling elements. This may further improve the dynamicproperties of the fin.

In a further embodiment of the dynamic fin according to the inventionthe first coupling element comprises a groove having a receiving openingwhich includes an inner protruding portion, wherein the second couplingelement comprises a tongue having an outer protruding portion. The innerand outer protruding portions may engage to each other in an assembleddynamic fin, wherein the engagement of the protruding portions provide alocking of the second fin section to the first fin section in adirection away from the opening of the groove, which is in the directionof the second axis. Preferably, at least one protrusion extends oversubstantially the whole length of the coupling element. The lockingfurther improves a sealing between the adjacent fin sections. Aclearance between the fin sections may be closed automatically at thehigh-pressure side (“concave” side) of the fin. Generally, a highpressure occurs at the concave side of the fin. The improved sealing mayprevent a leakage via the clearance of fluid from the high pressureside, so called lower camber side, to the low pressure side, the socalled upper camber side (convex or lee side) of the fin. Herewith, theeffectiveness of the fin may be further increased. The protrudingportions may further improve the dynamic fin to withstand bigger hydro-or aerodynamic forces in a direction along the fin. Advantageously, theprotruding portions may make the fin stronger.

In a further embodiment according to the invention the inner protrudingportion may be formed as an end stop. Herewith the end stop is internaland integral instead of an additional component like a pin, with thefirst coupling element, which advantageously may result in a simplermanufacturing of the fin. The internal positioned end stop may make thefin less susceptible for damages or contaminations from outside the fin.

In an embodiment the dynamic fin according to the invention comprises alocking element. The locking element may provide for locking a rotationof the fin sections. Preferably, the locking element may be used forlocking at least one extreme position of the fin sections. The lockingelement may be adjustable for changing an extreme position. In aparticular embodiment the locking element may be applied for locking anominal or mid position, wherein the fin is symmetrical over an axisextending in the second direction.

Further the invention relates to a watercraft, e.g. sailing ship orsurfboard, provided with a dynamic fin according to the invention. Thefin may be a keel, a rudder or a tunnel thruster. Generally, the finaccording to the invention may be useful for applications, wherein thefin is susceptible to a interchanging positive or negative dynamic load.The fin according to the invention may typically replace conventionalsymmetrical fins. The fin according to the invention may provide thesame effectiveness for opposite hydrodynamic loads.

Other aspects of the present disclosure will become apparent from thefollowing descriptions when considered in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A further elucidation of the invention will be given by the appendeddrawings which provide a practical embodiment of the invention, but maynot be considered in a limiting sense, wherein:

FIG. 1 shows a view in perspective of a dynamic fin according to theinvention;

FIG. 2 shows a view in more detail of an upper region of the dynamic finof FIG. 1;

FIG. 3 shows a cross-sectional view of a dynamic fin in a nominal andtwo extreme positions;

FIG. 4 shows a simplified cross-sectional view of a dynamic fin in anominal and an extreme position; and

FIG. 5 shows the cross-section of FIG. 3 in more detail, wherein a pairof coupling elements is shown.

DETAILED DESCRIPTION

FIG. 1 shows a dynamic fin according to the invention. The dynamic finis arranged as a fin which is suitable to serve as a fin for a surfboard. The fin has outer side surfaces, a base and a tip. The outer sidesurfaces are substantially smooth. The dynamic fin comprises twoparallelly arranged fin sections. For the application as a smart fin ina surfboard, the fin sections may be made from a plastic materialincluding eventually reinforcing fibres. The fin sections are madesufficient rigid to withstand dynamic loads. The dynamic fin is formedby a first fin section which has a rounded front edge which defines aleading edge and forms a front side of the dynamic fin. The fin has asharp edge at a tail which defines a trailing edge. During use a fluidmay flow backwards along the fin from the rounded front side to thetail. The dynamic fin has a cross-section which is shaped like anairfoil having a chord which defines an upper chamber and a lowerchamber.

FIG. 2 shows in a view in more detail an upper region of the dynamic finas shown in FIG. 1. The dynamic fin may be considered as orientated inan orthogonal coordinate system. The coordinate system comprises afirst, second and third axis. The fin sections extend in a longitudinaldirection along the first axis. The dynamic fin may be installed to awatercraft, in particular a surfboard, by two rotation shafts 3. Therotation shaft 3 is connected to the fin section and extends in adirection parallel to the first axis. The rotation shaft may be heavilyloaded and is therefore made of a strong material, like stainless steel.The rotation shaft 3 may be glued or clamped to the fin section 1, 2.The rotation shaft extends away from a mounting surface in a directionparallel to the first axis. The rotation shaft 3 is cylindrical at abottom region. The cylindrical part extends away from the mountingsurface and provides an accurate positioning of the fin section in amounting box. As shown in FIG. 1 the rotation shaft has further aconical part for centring the rotational shaft in a mounting box, e.g. aTuttle box. The geometry of the rotational shaft allows a user toquickly mount or demount the dynamic fin according to the invention.

Further, as shown in FIG. 1, the dynamic fin comprises a pair ofcoupling elements. The coupling elements comprise a first couplingelement 4 and a second coupling element 5. The first coupling element 4is formed as a groove which extends in the longitudinal direction alongan edge of the first fin section. The second coupling element 5 iscomplementary shaped to the first coupling element 4. As shown in FIG.1, the second coupling element 5 is formed by an outer tongue which iscomplementary shaped with respect to the first coupling element andextends in the longitudinal direction along a straight edge of the finsection. The coupling elements extend over substantially the wholelength of the edge of the fin section. This may improve the dynamicproperties of the fin, because occurring dynamic loads may be betterdistributed over adjacent fin sections.

The outer tongue has a constant shape which is symmetrical incross-section. The constant shape of the coupling elements becomessmaller in a direction away from the mounting surface. Herewith, the twofin sections 1, 2 can be mounted to each other by sliding the two finsections relative to each other in a direction parallel to the firstaxis. The connection of the fin sections is unambiguous and easy to makeby the user. A predefined amount of play has to remain between thecoupling elements to allow a certain rotational movement of the finsections relative to each other. The length dimension of the groove andtongue is designed such that after assembling of the fin sections, thispredefined amount of play is assured. In a possible embodiment, thegroove in the first fin section may have an end face for stopping thesliding movement of the second fin section. The tongue 5 extends fromthe base of the fin, the mounting surface 6, in a longitudinal directiontowards the tip and ends with a cross cut. After assembly the cross cutof the tongue 5 may be adjoined positioned to the end face of the groove4. Herewith the cross cut of the tongue functions as a stopper to stopthe sliding movement of the fin sections when they are assembled. Inanother embodiment, adjacent fin sections may be axially positioned byan external stopper, wherein the end face of the groove and the crosscut of the tongue are spaced apart over e.g. 2 mm. The external stopper,which aligns for instance mounting surfaces of adjacent fin sections,may simplify the manufacturing of the fin.

FIG. 3 shows a cross-sectional top view of the dynamic fin. The dynamicfin is shown in three different positions. The first position I shows anominal position, wherein the fin sections are aligned to each other.The resulting cross section is symmetrical in this position. Thesymmetrical cross section has an axis of symmetry in a direction of thesecond axis.

The back positioned fin section may be rotated around an axis which isparallel to the first axis of the coordinate system. The position II isan extreme position of the dynamic fin. The cross-section has acambered, substantially air foil shape. In position II the frontpositioned fin section is rotated clock wise, wherein the backpositioned fin section is rotated in a counter clockwise direction. Anend stop which is shown in more detail in FIGS. 4 and 5 is provided tolimit the rotational movement of the fin sections to define the extremepositions II, III. The shown extreme positions II, III in FIG. 3 are inmirror symmetry. Herewith, the dynamic fin may obtain similar camberedshapes in its two extreme positions, which makes the dynamic finaccording to the invention perfectly suitable to serve as a fin for asurfboard or sail ship. The dynamic fin according to the inventionprovides the same advantageous dynamic effects in opposite directions.In other words, the dynamic fin may generate an improved counterpressure to the tendency of the surfboard or sail ship to roll in bothsailing directions perpendicular to the wind direction.

FIGS. 4 and 5 show in more detail a view of the pair of couplingelements 4, 5. FIGS. 4 and 5 shows the same positions I, II as shown inFIG. 3. Bold arrows indicate the flow of fluid along the outer surfacesof the dynamic fin. In position II a pressure difference will occurbetween the opposite outer surfaces. This pressure difference is, as iswell known, responsible for the dynamic properties. It is important toprevent disturbances of the fluid flow. At the high pressure side of thefin, the outer side surfaces of the fin sections are smoothly alignedwith each other. This prevents disturbances at the high pressure side ofthe fin. It has appeared that a gap at the opposite side of the fincause hardly any disturbances to the dynamic properties.

As shown in FIGS. 4 and 5 in cross section, the second coupling element5 has a shape of a fungus. The fungus has a stem and a head which fitsincluding an amount of play into a smaller and broader part of thegroove 4. As shown in FIG. 4 the rotational movement of the fin sectionsis limited by an external end stop 7 and an internal end stop 8. Theexternal end stop 7 is positioned close to the outer surfaces of the finsections. The external ends top 7 limits the rotational movement of thefin sections. The internal end stop 8 limits also the rotationalmovement, but provides further a strong connection between the finsections in a direction of the fluid flow. The internal end stop 8 isobtained by providing an inner protrusion in the groove of the firstcoupling element and a corresponding outer protrusion on the tongue ofthe second coupling element 5. As a result the groove which has areceiving opening to receive the tongue 5 of the second coupling elementcomprises a smaller portion which locks the tongue 5.

The fin sections rotate in an extreme position as a result of adynamical load. Herewith no active operation by manually steering ordrive means is necessary to get the dynamic fin according to theinvention in one of the extreme positions. Herewith, the dynamic fin maybe classified as a passive fin, which makes it as in particular suitableto serve as a keel.

The end stops 7, 8 define contact areas between the fin sections. Thesecontact areas provide an additional advantage effect in that theyprevent also a leakage of fluid from one side of the fin to the otherside. A leakage of fluid would influence the pressure difference createdby the dynamic effect and is therefore not desired.

The smooth transition of the outer surfaces of the fin sections createdby the external stop 7 may prevent swirls in the passing fluid whichfurther increases the dynamic properties of the fin.

The smaller portion in the groove 4 is indicated with letter “b”. Thelarger portion on the tongue 5 is indicated with letter “a”. The smallerdimension “b” provide a lock to the broadened portion of the tongue 5 toremove the fin section in a direction away from the receiving opening.

FIG. 5 corresponds to FIG. 4 and shows a cross-sectional view of adynamic fin in a nominal I and an extreme position II. The groove 4 andthe tongue 5 have rounded parts. The rounded tongue fits within therounded groove. The rounded parts gives the fin sections 1,2 a freedomto rotate relatively to each other to get a cambered shape.Advantageously, the rounded parts and eventually other roundings in thecontour of the cross section may make the fin stronger. Unacceptablehigh local stresses may be prevented by the smooth contour.

Besides the shown embodiments, several alternatives are possible withoutleaving the scope of protection as defined by the appendant claims. In avariant the tongue may be formed at a tail fin section, wherein thegroove may be formed at a front fin section. For example, a furtherexternal stop may be created by a pin which may be adjustable to obtainadjustable extreme positions. The shown embodiment is designed as a finfor a surf board. However, the dynamic fin according to the invention isfurther applicable as for example a rudder, propeller, a rollstabilisation fin for ships, a spoiler or other aerodynamic surface.

Thus, according to the invention a dynamic fin is provided havingimproved functionality in that the fin sections are easier to mount anddemount. In addition, the manufacturing of the dynamic fin is furtherimproved by simplifying the design including the pair of couplingelements. A preferred embodiment is shown, wherein it is even possibleto manufacture the dynamic fin completely by a moulding process.

Although the present disclosure has been described and illustrated indetail, it is to be clearly understood that this is done by way ofillustration and example only and is not to be taken by way oflimitation. The scope of the present disclosure is to be limited only bythe terms of the appended claims.

I claim:

1. A dynamic fin comprising: at least two parallel arranged finsections; an orthogonal coordinate system including a first, a second,and a third axis defined by the at least two parallel arranged finsections; the at least two parallel arranged fin sections extend in adirection of the first axis wherein at least one of the fin sectionsincludes a rotational axis for installing the at least one fin sectionby a rotational shaft and the rotational axis extends in a direction ofthe at least one fin section and enables a rotational movement of the atleast one fin section; the dynamic fin further comprising at least oneend stop for stopping the rotational movement of the at least one finsection to define an extreme position, in which extreme position the atleast two parallel arranged fin sections provide a substantiallycantilevered shape to the dynamic fin; and wherein a first of the atleast two fin sections is in rotation, coupled to an adjacent second ofthe least two fin sections by a first coupling element and acomplementary second coupling element, and the first coupling element ispart of the first fin section and the second coupling element is part ofthe second fin section.
 2. The dynamic fin according to claim 1, whereinthe first coupling element is formed by a groove which extends in alongitudinal direction along an edge of the first fin section.
 3. Thedynamic fin according to claim 1, wherein the first coupling elementextends over substantially the whole length of the first fin section. 4.The dynamic fin according to claim 1, wherein the second couplingelement is formed by an outer tongue which is complementary shaped withrespect to the first coupling element and extends in a longitudinaldirection along an edge of the at least one fin section.
 5. The dynamicfin according to claim 1, wherein one or more of the first and secondcoupling elements comprise a symmetrical shape in cross section.
 6. Thedynamic fin according to claim 1, wherein one or more of the first andsecond coupling elements comprise, in the first direction, a constantshape in a cross section.
 7. The dynamic fin according to claim 6,wherein the at least one fin section comprises a base fin and tip,wherein the constant shape becomes smaller in a direction away from thebase.
 8. The dynamic fin according to claim 1, wherein the firstcoupling element encloses the second coupling element for mounting theat least two parallel arranged fin sections by an axially slidingmovement of the at least two parallel arranged fin sections relative toeach other.
 9. The dynamic fin according to claim 8, wherein a stopperis provided for stopping the axially sliding movement.
 10. The dynamicfin according to claim 2, wherein the groove of the first couplingelement comprises, in a cross section, an inner rounded part forreceiving the second coupling element, which second coupling elementcomprises an outer rounded part in a transversal cross section.
 11. Thedynamic fin according to claim 1, wherein the first coupling elementcomprises a groove having a receiving opening which includes an innerprotruding portion and wherein the second coupling element comprises atongue having an outer protruding portion for locking the second finsection to the first fin section in a direction away from the opening ofthe groove.
 12. The dynamic fin according to claim 11, wherein at theleast one end stop is formed by the inner protruding portion.
 13. Thedynamic fin according to claim 1, wherein the at least two parallelarranged fin sections are rotatable from one extreme position to anotherextreme position under a substantially constant resistance.
 14. Awatercraft comprising a dynamic fin according to claim
 1. 15. Thedynamic fin according to claim 14, wherein the dynamic fin is configuredas a keel or a rudder.
 16. The dynamic fin according to claim 14,wherein the dynamic fin is configured as a tunnel thruster.
 17. Thedynamic fin according to claim 14, wherein the dynamic fin is configuredas a propulsion element.
 18. The dynamic fin according to claim 1,wherein the dynamic fin is configured as a vane of a turbine.
 19. Thedynamic fin according to claim 1, wherein the dynamic fin is configuredas a propulsion element in a motor.
 20. The dynamic fin according toclaim 1, wherein the dynamic fin is configured as a spoiler.